Fat crystallization process



United rates Patent 3,059,009 FAT CRYSTALLIZATION PROCESS Dieter F.Schmid, Heidelberg, Germany, and Fredric .I.

Baur, Cincinnati, Ohio, assignors to The Procter &

glaimble Company, Cincinnati, Ohio, a corporation of o No Drawing. FiledSept. 21, 1961, Ser. No. 139,607 7 Claims. (Cl. 260-428) This inventionrelates to an improved crystallization process. More particularly, itrelates to the addition of certain crystal modifying agents to glycerideoils containing fatty materials which are insoluble in the oils, wherebyseparation of the insoluble fatty materials from the oils isfacilitated.

A large amount of vegetable glyceride oil is used as salad oil. Suchoils can serve as a base for various liquid salad dressings, providingan oily coating for salad ingredients. They are also used in mayonnaiseemulsions. Both salad oils and mayonnaise are usually kept underrefrigeration by the housewife. At temperatures of about 40 F. or lower,fatty materials will deposit out of many salad oils, causing them tohave a cloudy appearance. In mayonnaise, such crystal formation tends tobreak the emulsion, causing separation of fatty material from theaqueous portion.

If soybean oil is used as a salad oil it tends to develop acharacteristic beany odor and flavor. Even when it has been renderedcompletely odorless and flavorless by high-temperature steamdeodorization, the characteristic odor and flavor will return, in part,at least, due to the linolenic acid content of the oil.

It has been proposed that the stability of soybean oil against odor andflavor reversion can be increased by hydrogenation. However,hydrogenation decreases the unsaturation of unsaturated component fattyacids and also converts the unsaturated acids to higher-melting andless-soluble isomers. The oil must then be winterized by a processincluding cooling and subsequent separation of insoluble glycerides toremove materials which will solidify when the oil is refrigerated, andthereby cause undesirable salad oil performance and appearance. Otheroils such as cottonseed oil are given a similar Winterizing treatment.Insoluble fatty materials in oils such as corn oils are also removed bya cooling step, followed by a separation step.

Another important use of glyceride oils is in the paint industry. Oilsof particular interest are the so-called drying oils which formprotective coatings because of the ability of these oils to polymerizeor dry after they have been applied, thereby forming tough, adherent,impervious and abrasion-resistant films.

It is generally believed that the film-forming properties of drying oilsare related to their degree of unsaturation, andthat the films areformed by polymerization of double bonds present in unsaturated oils. Itis highly desirable, therefore, that oils suitable for use as dryingoils contain a large amount of triunsaturated glycerides, and relativelyfew trisaturated glycerides or mixed saturated-unsaturatedtriglycerides.

U.S. Patents 2,442,531 and 2,442,533, issued to E. W. Eckey on June 1,1948, disclose the directed rearrangement of triglycerides. By means ofthe process disclosed in these patents a substantial portion of mixedsaturatedunsaturated triglycerides is rearranged to form a largerproportion of highly saturated glycerides and highly unsaturatedglycerides. The more saturated glycerides in crystalline form are thenseparated from the rearranged and mixture, leaving an unsaturated oilvery suitable for use as a drying oil.

Special coating fats are required for coating of candies. These fatsmust have a high melting point so that they will not be greasy at normalroom temperatures. However, these fats must also melt in the mouth whenthe candy is eaten, and thus the presence of fats melting at too hightemperatures are undesirable. When oils such as hydrogenated palm kerneloil, and palm oil, either hydrogenated or unhydrogenated, are to be usedfor this purpose, it may be desirable to separate out highlysaturatedmaterials which would produce a waxy taste in the mouth. Suitableconfectioners fats can also be formed from the more saturated portionsof directed rearranged triglycerides.

At times it would be desirable to use palm oil as a major constituent ofa margarine oil. In certain geographic locations palm oil is cheaperthan other oils, and a supply of palm oil may be more readily availablethan a supply of some other oil. It has been found that the content ofhigh-melting insoluble fats in palm oil, at a temperature of 92 F., istoo high to produce a satisfactory margarine, since these insoluble fatswill impart a waxy taste in the mouth during eating. Separation of theinsoluble fats from the palm oil would increase its utility as amargarine constituent.

One of the main problems encountered in the separation of insolublefatty materials from glyceride oils has been the fact that the insolublefatty materials entrain a large amount of glyceride oil. In addition,conventional separation procedures are very slow.

It has now been found that by the process of this invention theseparation of insoluble fatty materials from liquid glyceride oils isgreatly facilitated, thereby permitting the recovery of a much largeramount of liquid oil than has heretofore been possible. In addition, therate of separation is greatly increased. As used herein the terminsoluole fatty materials is intended to include materials whichdissolve in oils at elevated temperatures and which will precipitate outof solution as the oils are cooled and allowed to stand.

It is therefore an object of this invention to provide a process formodifying insoluble fatty materials in glyceride oils whereby thesubsequent separation of the fatty materials is greatly facilitated.

It is a further object of this invention to provide an improved processfor making a salad oil.

Another object is to provide an improved method of making a drying oil.

Yet another object is to provide a method of making confectioners fatswhich have good eating quality.

Other objects and advantageous features will be app-arent from thefollowing detailed description.

In general, the process of this invention comprises the steps ofdissolving in a glyceride oil containing insoluble fatty material, at atemperature at which substantially all of said fatty material is insolution in said glyceride oil, from about 0.001% to 0.5%, by weight ofoil, of sucrose esterfied with an average of from about 15% to ofsaturated fatty acid having from 12 to 22 carbon atoms in the alkylchain and from 0 to unsaturated fatty acid having from 12 to 22 carbonatoms in the alkyl chain; cooling the glyceride oil to a temperature atwhich insoluble fatty material comes out of solution; and separating theinsoluble fatty material from the oil. The degree of esterificationshould be such that the ester contains an average of not more than about5 unesterified hydroxyl groups per sucrose molecule. Esters contain-,such as pyridine, amides, and sulfoxides.

ing more than that number of unesterified hydroxyl groups will be tooinsoluble to modify the fatty materials in the desired manner.

The sucrose ester exerts a modifying effect on the insoluble material sothat it comes out of solution in the form of large crystallineaggregates. These entrain a smaller amount of liquid fatty glyceridesduring separation than do crystals formed in the absence of the ester.

The process of this invention is generally applicable to any glycerideoils which contain fatty materials which will dissolve in the oils atelevated temperatures and which will crystallize out of solution whenthe oils are subsequently cooled and allowed to stand. For example, theremoval of insoluble fatty materials from oils which are conventionallywinterized to form salad oils, such as cottonseed oil, hydrogenatedsoybean oil, and corn oil is greatly facilitated. The process can beapplied to oils such as palm oil and palm kernel oil, eitherhydrogenated orunhydrogenated to form improved margarine oils orconfectioners fats.

Directed rearranged triglycerides can also be processed by thisinvention. Preferably the directed rearrangement iscarried out asdescribed in US. Patent 2,442,531, issued June 1, 1948, in whichtriglyceride oils are contacted with a low-temperature molecularrearrangement catalyst at such a temperature that the more highlysaturated triglycides are precipitated as they are formed during therearrangement of the glycerides in the oil. A list of suitablerearrangement catalysts is set forth in the aforementioned U.S. Patent2,442,531. However, it is to beunderstood that other suitablerearrangement catalysts and operating conditions can be used. As usedherein the term directed rearrangement is intended to denote a molecularrearrangement process directed for a greater tion of sucrose with fattyacids, fatty acidanhydrides, or 'fatty acid halides. They can also beprepared by interesterification of sucrose with fatty acid esters ofother polyhydric compounds in the presence of suitable solvents Othermethods of forming these esters can be used, and it is to be understoodthat the invention is not limited to any specific method of making theesters.

It is preferred that the oils to be processed be heated to a temperatureat which substantially all of the insoluble fatty material is in liquidform prior to slowly cooling the oil in which is dissolved the sucroseester. The ester can be added prior to or after heating. The exactconditions for cooling will vary with the amount of oil in the batch andthe amount of insoluble fatty material, but the optimum coolingconditions can be determined by those skilled in conventional oilgraining procedure.

The insoluble fatty materials are conveniently separated by conventionalfiltration procedures, but other methods of separation such ascentrifuging, can be used.

The improved results which can be achieved by the process of thisinvention are clearly illustrated by the following examples:

EXAMPLE I 250 g. of refined and bleached soybean oil, hydrogenated to aniodine value of 105, was mixed in a container with 0.1%, by weightofoil, of a vegetable oil ester of sucrose.

The vegetable oil ester was prepared by mixing togeether 300 g. ofsucrose, 500 g. of a mixture of 80% soybean oil and 20% cottonseed oilhydrogenated to an iodine value of 76, and 1250 ml. of pyridine, andheating the mixture to 240 F. Then 100 ml. of a solution containing 9 g.of sodium methoxide suspended in xylene was added as a catalyst andstirred for 4 hours. The catalyst Was inactivated with acetic acid andthe pyridine was substantially all removed by vacuum distillation.

The distillation residue was taken up in 700 ml. of a 4 to 1 mixture ofethyl acetate and n-butanol, and waterwashed. The Water-washed fattyproducts were recovered by evaporating the ethyl acetate-n-bntanolsolvent under a stream of nitrogen and using a steam bath. The fattyacid content of the product, as analyzed by ultraviolet spectrometry,was approximately as follows:

Percent Total saturated (approximately half palmitic acid and halfstearic acid) 16.9 Octadecenoic acid 75.0 Octadecadienoic acid 7.9Octadecatrienoic id V 0.2

An average of about 3 of the hydroxyl groups of the sucrose wereesterified.

The mixture of oil and additive was heated to F. for one hour. It wasthen placed for three days in a room held at a temperature of 40 F. Theresulting mixture of liquid and solid glycerides which had formed wasfiltered through a Buchner funnel using filter paper and suction. Thefollowing measurements were recorded of the total amount of oil passingthrough the filter at various time intervals, as compared with a similarsample containing no additive:

V Filtrate Volume (00.)

Time (min.)

Vegetable Oil Ester 0t Sucrose No Additive EXAMPLE n An ester of sucrosecontaining both saturated and unsaturated long-chain fatty acids wasdissolved in a onepound sample of refined cottonseed oil at a level of0.005% by weight. The fatty acid composition of the ester wasapproximately as follows:

Percent Total saturated (approximately half palmitic 19.0 79.5 1.4 Traceand half steaiic acids) Octadecenoic acid Octadecadienoic acidOctadecatrienoic a id About one-half of the hydroxyl groups of thesucrose were esterified. This oil, and also a sample of the oil withoutester, were heated to a temperature of 140 F.

with stirring. Thejsamples were cooled gradually to 60 F. and held atthat temperature for about 24 hours. They were then cooled slowly toa'temperature of 45 F. and held at that temperature for about 24 hoursuntil crystallization appeared to be substantially complete. 'Eachsample was vacuum filtered using, a Buchner fun- ;nel and filter paper.The filtration was continued until and then holding it as 40 F. for 3days.

the filter cake broke. The filtrates were weighed and the yield of oilcalculated. These data were as follows:

Filtration Yield Yield of Amt. Additive (Percent) Time Oil (gm.) Oil in)(Percent) None 487. 5 355 78. 5 0.005 312.0 367 80. 7

EXAMPLE III Filtration Yield of Yield of Amt. Additive (Percent) TimeOil (gm.) Oil (min) (Percent) None 12. 5 320 70. 5 0.005 l2. 5 349 76. 9

EXAMPLE IV Similar experiments were performed as in Examples 11 and IIexcept that the ester was sucrose esterified with an average of about 6palmitic and 3 oleic acid groups per molecule of sucrose. Filtrationdata on these samples were as follows:

Amt. of Filtration Yield 0! Yield of Oil Additive Time Oil Oil (Percent)(min.) (gm) (Percent) None 487. 5 355 78. 5 Cottonseed 0.005 201. 0 35980. 2 0.01--." 240. 3 372 83. 3 Hydrogenated soybean oil.-- {None 12. 5320 70. 5 0.005 7. 5 310 68.3

In the case of the soybean oil, although there was only a slightlysmaller yield, the filtration time is greatly decreased. Thesubstitution of esters using other combinations of saturated andunsaturated fatty acids having from 12 to 22 carbon atoms in the alkylchain, as hereinbefore set forth, and also their use in other oils suchas corn oil, and directed rearranged glyceride oils, will providecomparable results on filtration.

The practice of the process of this invention in the removal of fattymaterials which are insoluble in glyceride oils at higher temperaturesis illustrated by the following example:

EXAMPLE V Soybean oil was hydrogenated to an iodine value of 105 andwinterized by holding it at 50 F. for 2 weeks, The oil was then vacuumfiltered. A mixture was formed containing 95% of the clear oil filtrateand 5% of a saturated triglyceride containing about 2 palmitic acidgroups and 1 stearic acid group per molecule. This saturatedtriglyceride had an iodine value of 0.012. To the mixture was added0.1%, by weight, of the sucrose ester of Example I. 250 gm. samples ofthe oil mixture with and without added ester were heated to 140 F. forone hour to destroy all crystal nuclei and then cooled to 80 F. and heldat that temperature for 3 days to permit crystals to form. The resultingmixtures of insoluble fatty material and glyceride oil were filteredthrough a Buchner funnel using filter paper and vacuum. The followingmeasurements were recorded of the total amounts of oil passing throughthe filters at various time intervals.

1 N 0t measured.

Comparable results will be achieved by substitution in the foregoingexample of oils such as directed rearranged glyceride oils, hydrogenatedvegetable oils and other glyceride oils containing fatty materialsinsoluble in these oils at higher temperatures.

Although it is to be understood that the invention is not to be limitedby any theory, it is believed that esters suitable for improving thefiltration of oils for the purpose of separating insoluble fats fromoils should contain a substrate-similar and a substrate-dissimilarmoiety in the molecule. In the case of the aforementioned systems fattyacid chains in the fats and in the sucrose ester are similar. Thesucrose portion of the additive represents a polyhydric compound whichis dissimilar from that of the fats.

It is also believed that it is important that materials added asfiltration aids bear some relation in melting point and/ or solubilityto the fats which are to be separated by filtration. These aids shouldbe made with fatty acids having neither too high nor too low a meltingpoint, so that the modifier will have a tendency to deposit on theincipient crystal nuclei as they are formed, thereby modifying the fatcrystals. This results in the formation of crystal aggregates (around acrystallization center) which are compact and not feathery and are moreeasily filtered.

Further, it is believed that if the additive has too high a meltingpoint of too low a solubility in the oil, nuclei of additive will tendto form before the fat nuclei are formed, and the additive may act as anucleating agent for the fat, forming more nuclei than would normallyappear in the fat. As a result the fat crystal aggregates will be morenumerous and filtration will be more difficult.

Although specific examples have been given to illustrate the invention,it is to be understood that the invention is not to be limited to theseexamples, and that variations in the processing condiitons which willsuggest themselves to those skilled in the art are intended to bewitln'n the scope of the invention. It will further be appreciated thatsucrose esters used in commercial practice usually will be a mixture ofvarious esters and that the specified proportions of fatty acidsrepresent average values for such mixtures.

This is a continuation-in-part of application Serial No. 845,642, filedOctober 12, 1959.

What is claimed is:

1. The method of separating insoluble fatty material from glyceride oilwhich comprises the steps of dissolving in said glyceride oil, at atemperature at which substantially all of said fatty material is insolution, from about 0.001% to 0.5%, by weight of oil, of sucroseesterified with an average of from about 15% to saturated fatty acidhaving from 12 to 22 carbon atoms in the alkyl chain and from 0 to ofunsaturated fatty acid having from 12 to 22 carbon atoms in the alkylchain; said ester containing not more than 5 unesterified hydroxylgroups; cooling the glyceride oil to a temperature at which insolublefatty material comes out of solution; and separating the insoluble fattymaterial from the oil.

2. The method according to claim 1 wherein the sucrose is esterifiedwith a mixture of fatty acids comprising 7 essentially from 8% to 16%palmitic acid, and 5% to 15% stearic acid, the total combined saturatedfatty acid content being from about 15% to 27%, and the balance of thefatty acids being essentially from 59% to 76% octadecenoic acids and 3%to 9% octadecadienoic acids. 3. The method according to claim 1 whereina solution of sucrose ester in oil is heated to a temperature at whichsubstantially all of the insoluble fatty material is dis solved, and themixture is thereafter slowly cooled to a temperature at which fattycrystals will form.

4. The method according to claim 1 wherein the oil is V heated to atemperature at which substantially all of the insoluble fatty materialis dissolved, the sucrose ester is dissolved in said heated oil, and theresulting mixture is slowly cooled to a temperature at which fattycrystals will form.

5. The method according to claim 1 wherein the oil is cottonseed oil.

6. The method according to claim 1 wherein the oil is hydrogenatedsoybean oil.

7. The method according to claim '1 wherein the oil is -a directedrearranged glyceride oil.

References Cited in the file of this patent UNITED STATES PATENTS UNITEDSTATES PATENT OFFICE CERTIFICATE OF CGRRECTION Patent No, 3,059,009October 16 1962 Dieter F, Schmid et a1.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 3 lines 6'? and 68 for "togeether" read together column 6,, inthe table last column opposite 4" for read (l) line 51 for "condiitons"read conditions Signed and sealed this 30th day of April 1963a (SEAL)Attest:

ERNEST w. SWIDER DAVID LADD Attesting Officer Commissioner of Patents

1. THE METHOD OF SEPARATING INSOLUBLE FATTY MATERIAL FROM GLYCERIDE OILWHICH COMPRISES THE STEPS OF DISSOLVING IN SAID GLYCERIDE OIL, AT ATEMPERATURE AT WHICH SUBSTANTIALLY ALL OF SAID FATTY MATERIAL IS INSOLUTION, FROM ABOUT 0.001%TO 0.5%, BY WEIGHT OF OIL, OF SUCROSEESTERIFIED WITH AN AVERAGE OF FROM ABOUT 15% TO 80% SATURATEDD FATTYACID HAVING FROM 12 TO 22 CARBON ATOMS, IN THE ALKYL CHAIN AND FROM 0 TO85% OF UNSATURATED FATTY ACID HAVING FROM 12 TO 22 CARBON ATOMS IN THEALKYL CHAIN; SAID ESTER CONTAINING NOT MORE THAN 5 UNESTERIFIED HYDROXYLGROUPS; COOLING THE GLYCERIDE OIL TO A TEMPERATURE AT WHICH INSOLUBLEFATTY MATERIAL COMES OUT OF SOLUTION; AND SEPARATING THE INSOLUBLE FATTYMATERIAL FROM THE OIL.